src/condition.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <stdlib.h>
  23 #include <errno.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26
  27 #include "util.h"
  28 #include "condition.h"
  29
  30 Condition* condition_new(ConditionType type, const char *parameter, bool trigger, bool negate) {
  31         Condition *c;
  32
  33         c = new0(Condition, 1);
  34         c->type = type;
  35         c->trigger = trigger;
  36         c->negate = negate;
  37
  38         if (parameter)
  39                 if (!(c->parameter = strdup(parameter))) {
  40                         free(c);
  41                         return NULL;
  42                 }
  43
  44         return c;
  45 }
  46
  47 void condition_free(Condition *c) {
  48         assert(c);
  49
  50         free(c->parameter);
  51         free(c);
  52 }
  53
  54 void condition_free_list(Condition *first) {
  55         Condition *c, *n;
  56
  57         LIST_FOREACH_SAFE(conditions, c, n, first)
  58                 condition_free(c);
  59 }
  60
  61 static bool test_kernel_command_line(const char *parameter) {
  62         char *line, *w, *state, *word = NULL;
  63         bool equal;
  64         int r;
  65         size_t l, pl;
  66         bool found = false;
  67
  68         assert(parameter);
  69
  70         if (detect_virtualization(NULL) > 0)
  71                 return false;
  72
  73         if ((r = read_one_line_file("/proc/cmdline", &line)) < 0) {
  74                 log_warning("Failed to read /proc/cmdline, ignoring: %s", strerror(-r));
  75                 return false;
  76         }
  77
  78         equal = !!strchr(parameter, '=');
  79         pl = strlen(parameter);
  80
  81         FOREACH_WORD_QUOTED(w, l, line, state) {
  82
  83                 free(word);
  84                 if (!(word = strndup(w, l)))
  85                         break;
  86
  87                 if (equal) {
  88                         if (streq(word, parameter)) {
  89                                 found = true;
  90                                 break;
  91                         }
  92                 } else {
  93                         if (startswith(word, parameter) && (word[pl] == '=' || word[pl] == 0)) {
  94                                 found = true;
  95                                 break;
  96                         }
  97                 }
  98
  99         }
 100
 101         free(word);
 102         free(line);
 103
 104         return found;
 105 }
 106
 107 static bool test_virtualization(const char *parameter) {
 108         int r, b;
 109         const char *id;
 110
 111         assert(parameter);
 112
 113         if ((r = detect_virtualization(&id)) < 0) {
 114                 log_warning("Failed to detect virtualization, ignoring: %s", strerror(-r));
 115                 return false;
 116         }
 117
 118         b = parse_boolean(parameter);
 119
 120         if (r > 0 && b > 0)
 121                 return true;
 122
 123         if (r == 0 && b == 0)
 124                 return true;
 125
 126         return streq(parameter, id);
 127 }
 128
 129 bool condition_test(Condition *c) {
 130         assert(c);
 131
 132         switch(c->type) {
 133
 134         case CONDITION_PATH_EXISTS:
 135                 return (access(c->parameter, F_OK) >= 0) == !c->negate;
 136
 137         case CONDITION_PATH_IS_DIRECTORY: {
 138                 struct stat st;
 139
 140                 if (lstat(c->parameter, &st) < 0)
 141                         return !c->negate;
 142                 return S_ISDIR(st.st_mode) == !c->negate;
 143         }
 144
 145         case CONDITION_DIRECTORY_NOT_EMPTY: {
 146                 int k;
 147
 148                 k = dir_is_empty(c->parameter);
 149                 return !(k == -ENOENT || k > 0) == !c->negate;
 150         }
 151
 152         case CONDITION_KERNEL_COMMAND_LINE:
 153                 return test_kernel_command_line(c->parameter) == !c->negate;
 154
 155         case CONDITION_VIRTUALIZATION:
 156                 return test_virtualization(c->parameter) == !c->negate;
 157
 158         case CONDITION_NULL:
 159                 return !c->negate;
 160
 161         default:
 162                 assert_not_reached("Invalid condition type.");
 163         }
 164 }
 165
 166 bool condition_test_list(Condition *first) {
 167         Condition *c;
 168         int triggered = -1;
 169
 170         /* If the condition list is empty, then it is true */
 171         if (!first)
 172                 return true;
 173
 174         /* Otherwise, if all of the non-trigger conditions apply and
 175          * if any of the trigger conditions apply (unless there are
 176          * none) we return true */
 177         LIST_FOREACH(conditions, c, first) {
 178                 bool b;
 179
 180                 b = condition_test(c);
 181
 182                 if (!c->trigger && !b)
 183                         return false;
 184
 185                 if (c->trigger && triggered <= 0)
 186                         triggered = b;
 187         }
 188
 189         return triggered != 0;
 190 }
 191
 192 void condition_dump(Condition *c, FILE *f, const char *prefix) {
 193         assert(c);
 194         assert(f);
 195
 196         if (!prefix)
 197                 prefix = "";
 198
 199         fprintf(f,
 200                 "%s%s: %s%s%s\n",
 201                 prefix,
 202                 condition_type_to_string(c->type),
 203                 c->trigger ? "|" : "",
 204                 c->negate ? "!" : "",
 205                 c->parameter);
 206 }
 207
 208 void condition_dump_list(Condition *first, FILE *f, const char *prefix) {
 209         Condition *c;
 210
 211         LIST_FOREACH(conditions, c, first)
 212                 condition_dump(c, f, prefix);
 213 }
 214
 215 static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
 216         [CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
 217         [CONDITION_PATH_EXISTS] = "ConditionPathExists",
 218         [CONDITION_NULL] = "ConditionNull"
 219 };
 220
 221 DEFINE_STRING_TABLE_LOOKUP(condition_type, ConditionType);